Iklwa
Great! Yes, I considered spark detector for alpha particles. But I don't want to spend time with tinkering and doing something homemade with unclear results. Instead I can afford professional equipment that can give me trustworthy results. Once all details about the experiment are found then it could be good to try to make the things as cheap as possible. I think next week I will receive my new alpha detector.

Truth is, I made some exploratory tests today with something that could be schematically summarized like in the diagram below, only with steel parts instead of Ni and Ti, and unfortunately no radiation monitoring. The sodium carbonate solution could be made into a gel-like consistency and still work relatively well as an electrolyte as long as it's kept hydrated, although it will keep conducting a current down to an apparently very low water content. The cell is intended to be open.

So if sodium carbonate is ok, then the only thing left to know, for me at least, is if a Ti wire or wire bundle (twisted wires, etc) would still be good to use.

Why disassemble lithium batteries when a few euro/dollars could buy you 1 Kg of NaOH/KOH, or Na2CO3/K2CO3 ?

NaOH (caustic soda) and Na2CO3 (washing soda) could be easily found in a grocery store, but the latter is safer to handle (hydroxide solutions are corrosive).

Unless there are specific reasons for using LiOH (possibly, the Li could get more easily intercalated into the cathode---I think I've read a suggestion along these lines in a report), better solutions exist in my opinion. As a side note, alkaline batteries typically use KOH as an electrolyte.

Re: alkali or other hydrides. Do not assume classical "collisional" physics branching ratios--- many, or even all, of us likely do not actually understand the transition states / intermediate steps for the low activation energy paths and outcomes implied there.

Again, caution, small and shielded might be an important safety consideration--- A suddenly "successful" 1000 X (or far more) of peak power (whether alpha or not). Risky for unprepared amateurs or even unprepared professionals.

Titanium vaping wire could also be a suitable Ti source. I was thinking (for a potential experiment---I haven't purchased anything yet) of winding a couple meters or more of 32 AWG or 34 AWG Ti wire around a rigid metallic core. The surface/volume ratio might be comparable to the Ti flakes used by JohnyFive (depending on their specifications), with the advantage of higher practicality.

I was exploring the usage of an all-metallic construction also for safety purposes, actually. Over the months in some of my (silly) tests I've had a few small but sharp H2-O2 explosions which so far haven't shattered anything, but I guess it's only a matter of time/luck before they do. However this is only from the point of view of known chemical reactions.

That would be difficult to tell without adequate radiation monitoring. So far (in other experiment types than the ones described in this thread) I've used a method involving checking out the EMI produced during arc discharges, with inconclusive results.

Most immediate dangers from these experiments are likely chemical. For example with some materials (e.g. carbon, graphite) under certain conditions a persistent foam containing pockets of explosive H2-O2 mixture can easily form. This is less of a problem with the materials used for these JohnyFive replications, but I'd still want to prevent possible dangers. Then there also are other hazards like possible chemical burns when hydroxides are used, etc. Sodium carbonate on that regard is only slightly irritant.

By the way---so that it doesn't just remain a "what if" proposal---the improvised battery-like electrolytic cell in the diagram I posted earlier ended up being something like in the photo below. Contrarily to expectations it didn't work as expected compared to the initial "wafer" implementation. A problem was the electrolyte bubbling/boiling and getting displaced away even when applying 5V, and I don't have at the moment a power supply allowing finer control than 5V or 12V. So I guess that in practice I'd have to use a more traditional/flexible electrolytic setup.

Note we face risk and profit from danger. This is what women, men, [...]do - to advance culture.

However, when the men and women involved are not informed of the danger to the level of understanding of the risks involved, it is generally concluded they are incapable of giving 'informed consent'. Then, the person subjecting them to the dangerous conditions will be held liable either criminally or civilly as is appropriate.